Trimmed odd bits of crust (3)
I believe the answer is:
cut
'trimmed' is the definition.
(synonyms)
'odd bits of crust' is the wordplay.
'odd bits of' indicates alternate letters.
The alternate letters of 'crust' are 'CUT'.
(Other definitions for cut that I've seen before include "Shorten; remove" , "Reduction in power" , "Reap" , "reduced" , "drunk" .)